package com.dearbinge.utils;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class ListToTree {

	/**

	- listToTree
	- <p>方法说明<p>
	- 将JSONArray数组转为树状结构
	- @param arr 需要转化的数据
	- @param id 数据唯一的标识键值
	- @param pid 父id唯一标识键值
	- @param child 子节点键值
	- @return JSONArray
	*/
	public static JSONArray listToTree(JSONArray arr,String id,String pid,String child){
	   JSONArray r = new JSONArray();
	   JSONObject hash = new JSONObject();
	   //将数组转为Object的形式，key为数组中的id
	   for(int i=0;i<arr.size();i++){
	  JSONObject json = (JSONObject) arr.get(i);
	  hash.put(json.getString(id), json);
	   }
	   //遍历结果集
	   for(int j=0;j<arr.size();j++){
	  //单条记录
	  JSONObject aVal = (JSONObject) arr.get(j);
	  //在hash中取出key为单条记录中pid的值
		   System.out.println(j);
	  JSONObject hashVP = (JSONObject) hash.get(aVal.get(pid).toString());
	  //如果记录的pid存在，则说明它有父节点，将她添加到孩子节点的集合中
	  if(hashVP!=null){
	     //检查是否有child属性
	     if(hashVP.get(child)!=null){
	        JSONArray ch = (JSONArray) hashVP.get(child);
	        ch.add(aVal);
	        hashVP.put(child, ch);
	     }else{
	        JSONArray ch = new JSONArray();
	        ch.add(aVal);
	        hashVP.put(child, ch);
	     }
	  }else{
	     r.add(aVal);
	  }
	   }
	   return r;
	}
	public static void main(String[] args){
	   List<Map<String,Object>> data = new ArrayList<>();
	   Map<String,Object> map = new HashMap<>();
	   map.put("id",1);
	   map.put("pid",0);
	   map.put("name","甘肃省");
	   data.add(map);
	   Map<String,Object> map2 = new HashMap<>();
	   map2.put("id",2);
	   map2.put("pid",1);
	   map2.put("name","天水市");
	   data.add(map2);
	   Map<String,Object> map3 = new HashMap<>();
	   map3.put("id",3);
	   map3.put("pid",2);
	   map3.put("name","秦州区");
	   data.add(map3);
	   Map<String,Object> map4 = new HashMap<>();
	   map4.put("id",4);
	   map4.put("pid",0);
	   map4.put("name","北京市");
	   data.add(map4);
	   Map<String,Object> map5 = new HashMap<>();
	   map5.put("id",5);
	   map5.put("pid",4);
	   map5.put("name","昌平区");
	   data.add(map5);
	   System.out.println(JSON.toJSONString(data));
	   JSONArray result = listToTree(JSONArray.parseArray(JSON.toJSONString(data)),"id","pid","children");
	   System.out.println(JSON.toJSONString(result));
	}


}
